Berkshire booked gains from its insurance businesses, after the sector was battered early last year by disasters including the earthquake and tsunami in Japan. The firm's manufacturing, service and retail businesses were also a source of strength, as were its derivatives bets.

Berkshire's shareholders will gather in Nebraska on Saturday for the company's annual meeting, where the so-called Oracle of Omaha will likely face questions about his health and his succession plans.

In a letter to shareholders last month, Buffett disclosed that he had been diagnosed with prostate cancer, though the 81-year-old claimed the condition "is not remotely life-threatening or even debilitating in any meaningful way." Additional tests, he added, didn't reveal incidence of cancer anywhere else in his body.

Buffett has yet to publicly reveal a succession plan, though he says he has already informed Berkshire's board about his preferred candidates. Upon his departure, Buffett's job will be divided between a CEO in charge of operations and one or more executives in charge of investments.

Buffett has said that two investment managers who recently joined the company, Todd Combs and Ted Weschler, "will be handling a few billion dollars in 2012, but they have the brains, judgment and character to manage our entire portfolio" when he and Berkshire vice chairman Charlie Munger are no longer running the company.

Ajit Jain, who heads the firm's reinsurance business, has been mentioned by Berkshire-watchers as a possible successor on the operations side.

Buffett's son, Howard, is in line to follow as chairman of Berkshire Hathaway upon his father's death, though Howard will not be involved in strategy or day-to-day decisions.

Berkshire shares had a rare down year in 2011, slipping 4.7%, even as the broader market stayed mostly flat. Over the past two decades, the company's stock has gained more than thirteen-fold, while the S&P 500 Index is up about three-fold.